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Cellulose diacetate film was first created by the German chemists Arthur Eichengrün and Theodore Becker, who patented it under the name Cellit, from a process they devised in 1901 for the direct acetylation of cellulose at a low temperature to prevent its degradation, which permitted the degree of acetylation to be controlled, thereby avoiding total conversion to its triacetate.
Cellulose acetate is also known as "safety" film and started to replace nitrate film in still photography in the 1920s. [1] There are several types of acetate that were produced after 1925, which include diacetate (c. 1923 – c. 1955), acetate propionate (1927 – c. 1949), acetate butyrate (1936–present), and triacetate (c. 1950 – present). [1]
Cellulose acetate film, made from cellulose diacetate and later cellulose triacetate, was introduced in 1934 as a replacement for the cellulose nitrate film stock that had previously been standard. When exposed to heat or moisture, acids in the film base begin to deteriorate to an unusable state, releasing acetic acid with a characteristic ...
It can happen during a film screening when a frame becomes stuck in the projector's film gate. Acetate films are also subject to degradation over time. With exposure to heat, moisture, or acids, the acetyl groups are broken from their molecular bonds to the cellulose. The now free acetic acid is released into the air. Acetic acid is vinegar ...
Cellulose acetate film stocks are at risk of vinegar syndrome, which causes a vinegar like odor due to a reaction when moisture of the film interact with the air in the environment. [8] Whereas polyester-backed films are not susceptible to vinegar syndrome or flammable, but over time film, generally has the possibility to shrink, wrap, or have ...
Its high flammability was legendary since it self-ignites when exposed to temperatures over 150 °C in front of a hot movie-projector beam. While celluloid film was standard for 35mm theatrical productions until around 1950, motion-picture film for amateur use, such as 16mm and 8mm film, were on acetate "safety base", at least in the US.
The acetate base of the film degrades into acetic acid under non-ideal conditions, causing what is known as vinegar syndrome. Redox is the oxidation of the surface of the film and is often found in higher humidity areas. Regardless of temperature, blemishes (REDOX) appear on film and are caused by oxidation of materials stored with or near film.
The color degradation is the result of the dyes used in the color processes. Because color processing results in a less stable image than traditional black-and-white processing, black-and-white pictures from the 1920s are more likely to survive long-term than color films and photographs from after the middle 20th century.